An ever increasing population of very low birth weight infants is surviving the intensive care nursery. These infants present an increased likelihood of sustaining insults to the central nervous system (CNS). Many will suffer impairments including cognitive deficits and neurological soft signs severe enough to preclude normal school progress. Occult injury to the CNS which may involve certain brainstem structures has been implicated in a variety of these developmental disorders. Standard clinical test for identifying subtle lesions are indirect, uncertain and must await childhood before they can be properly applied. Moreover, functional aspects of CNS development are not taken into account. Little is known about neurophysiological maturation and how it relates to subsequent difficulty in pre term infants. The objective of this research is to increase our understanding of CNS development and to improve classification of very low birth weight infants with regard to outcome. By including direct (noninvasive) measures of CNS (the brainstem auditory evoked potential, BAEP) activity in the assessment procedure, we hope to be able to detect covert handicaps as soon as possible. Recent studies show that focal as well as general neuropathy may be reflected in BAEP recordings and that "high risk" infants are distinguishable from healthy controls in early infancy. Very low birth weight (less than 1250g) infants will be followed longitudinally through five years of age. Measures of intellectual status and specific cognitive abilities will include: the Bayley Scales at 3, 6, 12 and 24 months; the Stanford-Binet at 3, 4 and 5 years; the Beery Test of Visual-Motor Integration, the Draw-A-Person Test and the Illinois Test of Psycholinguistic Ability at 4 and 5 years of age. Standard neurological examinations will also be performed on a regular basis. In addition, perinatal risk factors, a well as clinical judgements, will be obtained. Multivariate models will be employed to determine the interactions and interrelationships between and among all pertinent variables.